Device and method for skin treatment

Abstract

A device and a method for fractional skin treatment. The device employs two diffractive optical elements. One of the diffractive optical elements provides two coaxial laser beams and another diffractive optical element splits the two coaxial laser beams into a plurality of beamlets. A lens arranged to receive the plurality of the laser beams and to focus them in a skin treatment plane. The lens forms an image where each of the beamlets is imaged as a spot with a high intensity central area and a lower intensity area surrounding the central area.

What is claimed is: 
     
       1. A device for treating biological tissue, comprising:
 a laser configured to provide a laser beam; 
 a first diffractive optical element configured to receive the laser beam and transform distribution of energy in the laser beam to a central spot and a surrounding ring of energy; 
 a second diffractive optical element configured to receive the laser beam with transformed distribution of energy and to split it into at least two laser beams; and 
 a lens arranged to receive the at least two laser beams and to focus the at least two laser beams and in a skin treatment plane, 
 wherein a separation angle of the first diffractive optical element supports diameter of a ring-shaped beam of 0.2 mm to 0.5 mm; and 
 wherein a separation angle of the second diffractive optical element is designed to set inter-spot distance between beamlets of 0.2 mm to 1 mm. 
 
     
     
       2. The device of  claim 1 , wherein the laser provides a single transversal mode (TEM 00 ) laser beam. 
     
     
       3. The device of  claim 1 , wherein the first diffractive optical element is a diffractive axicon. 
     
     
       4. The device of  claim 1 , wherein the first diffractive optical element transforms distribution of energy of incident laser beam into a ring-shaped laser beam and a central laser beam. 
     
     
       5. The device of  claim 4 , wherein the ring-shaped laser beam and the central laser beam are coaxial beams. 
     
     
       6. The device of  claim 4 , wherein a different ratio of laser intensity is coupled into the ring shaped laser beam and the central laser beam and wherein the ratio is a variable ratio. 
     
     
       7. The device for skin treatment of  claim 4 , wherein a lens forms in an image plane an image of the ring-shaped beam surrounded by an image of a central laser beam. 
     
     
       8. The device of  claim 1 , wherein centers of the image of a ring-shaped beam surrounded by an image of a central laser beam are located on a same grid points. 
     
     
       9. The device of  claim 1 , wherein the second diffractive optical element is a diffractive beam splitter.